Petroleum cuts, and in particular bases for fuels, gasolines, kerosines and gas oils, contain aromatic compounds the concentration of which has to be further and further reduced under new or future legislation limiting the amount of aromatic compounds in the above fuels.
Current processes for hydrogenating aromatic compounds in solvents or aromatic petroleum cuts such as kerosines or gas oils use noble metal type catalysts, for example platinum, deposited on an alumina support with a high specific surface area. However, such metals are highly sensitive to poisoning by sulphur-containing and nitrogen-containing compounds present in the feeds and thus such feeds have to be desulphurised and denitrogenated to a very great extent before treating them using a catalyst based on a noble metal.
It is thus important to produce aromatic compound hydrogenation catalysts in solvents or in aromatic petroleum cuts such as kerosines and gas oils which are highly active in the presence of sulphur and/or nitrogen and/or oxygen so as to reduce the severity of prior hydrotreatment and to achieve even higher degrees of hydrogenation.
Catalysts based on platinum and palladium have been described for the properties for hydrogenating aromatic compounds. In the case of using an alumina type support (United States patent U.S. Pat. No. 3,943,053), it is reported that it is necessary to precisely control the metal contents, as well as the preparation conditions. The use of supports based on silica-alumina has also been reported. Examples are U.S. Pat. No. 4,960,505, U.S. Pat. No. 5,308,814 and U.S. Pat. No. 5,151,172. Those catalysts are based on a highly specific zeolite and have the disadvantage of requiring selective deposition of noble metals onto the zeolite.